var documentImg = document.images;
var arrowOn;
var arrowOff;

if (documentImg) {
  arrowOn = new Image();
  arrowOn.src = "../images/freccia_on.gif";
  arrowOff = new Image();
  arrowOff.src = "../images/freccia_off.gif";
}

function switchArrow(arrow_id) {
  if (documentImg) {
    var arrowId = 'arrow_' + arrow_id
    document[arrowId].src = (document[arrowId].src.indexOf('freccia_on.gif') != -1) ? arrowOff.src : arrowOn.src;
  }
}

function showHideMenu(menuId) {
  var elem = document.getElementById("menu_" + menuId);
  if (elem.className == "show")
    elem.className = "hide";
  else
    elem.className = "show";
}

function highlightPhone(elem) {
  if (elem.className == "leftactive")
    elem.className = "lefthover";
  else
    elem.className = "leftactive";
}